AMO Bug - When addon is installed, the button still says '+ Add to Firefox'

Add-ons addons.mozilla.org
#1

I don’t know if this is intended or a bug, but if you have installed an addon, then visit that page on AMO, the button still says + Add to Firefox.

Should it not say something else like Update Now? Or check and say Update Now if your version is out-of-date, then hide the button if the addon is up-to-date?

Also while the page is loading, the button is temporarily blue, and says Download Now, nut it changes to normal after the page has finished loading.

#2

AMO cannot know whether an extension is installed or not. I don’t think it’s a good idea to expose the list of installed add-ons to websites. We could do it for AMO only, but extensions could easily extend that feature and send a list of installed extensions to another server.